Less than half of the voucher students in Louisiana scored at grade level or above on key tests and are 18 percentage points behind the statewide average, the state Department of Education announced Friday.

Vouchers are state aid that allow some low-income students at troubled public schools to attend private or parochial schools. About 7,100 students get the assistance, which was made statewide in 2012.

However, the latest tally on how those students are faring shows that 47 percent scored at grade level or higher on state-mandated assessments in 2014-15 compared to a statewide average of 65 percent.

In a prepared statement, the department noted the achievement gap has dropped from 32 percentage points for the 2010-11 school year to 18 points today. Since vouchers went statewide in 2012-13, instead of New Orleans only, the gap has narrowed by 9 percentage points.

The gap refers to the difference in how students who get vouchers did on state tests compared to the statewide average.

“This steady improvement is largely due to a state accountability system that uses state assessments to establish performance targets and to act quickly when schools struggle,” the department said in a prepared statement.

The latest results may reignite debate on the merits of vouchers, which were expanded statewide as part of former Gov. Bobby Jindal’s education overhaul in 2012.

Jindal and other backers of the aid say they offer students and their families a way out of troubled or even failing public schools.

Opponents contend the assistance has failed to produce the promised gains in student performance and that vouchers are a drain on dollars for traditional public schools.

In addition, Gov. John Bel Edwards may push for curbs on which students can qualify for vouchers during the regular session that begins March 14.

The program is costing the state $42 million this year, another issue in a session when Louisiana’s $2 billion shortfall will dominate debates.

The aid averages $5,500 per student.

Debbie Meaux, president of the Louisiana Association of Educators, a longtime critic of vouchers, said Friday the department needs to release more information about the program, including the quality of students who qualify.

“I understand the idea of parental choice,” Meaux said. “However, there has to be accountability and transparency whenever using state dollars.”

The test results come on the heels of a recent national report that said vouchers in Louisiana are actually hurting student achievement.

Voucher recipients suffer more academically in their new schools than if they had remained in their troubled public schools, according to a review done by the National Bureau of Economic Research in Cambridge, Massachusetts.

The study was based on the first year of the statewide voucher system — 2012-13.

Backers downplayed the report and said voucher students have shown steady gains since that first year.

Another report on how voucher students are faring by Tulane University and other schools is set for release Monday.

Low-income students who attend public schools rated C, D or F are eligible for the assistance.

State law requires the department to issue a report on how voucher and other choice programs are doing.

Follow Will Sentell on Twitter, @WillSentell. For more coverage of Louisiana government and politics, follow our Politics blog at http://blogs.theadvocate.com/politicsblog/.